Assembly of the triple helix of collagen is being studied in terms of a ribosomal assembly site. Intact alpha-chains are to be synthesized in a cell free system and their interaction properties determined. Alternatively, nascent polyribosome-bound collagen molecules, pepsin resistant, will be examined by chain-type. The factors involved in formation of collagen microfibrils are being explored utilizing a pH-jump procedure for preparation of microfibrils from solution. The aim of this study is to distinguish between the contributions of the molecular end-regions and helical regions in the molecular interaction leading to the development of the native fibril packing arrangement. Helical and end-regions from Type I and Type IV collagens are being studied.